Impact of contact and access resistances in graphene field-effect transistors on quartz substrates for radio frequency applications.

High-frequency performance of graphene field-effect transistors (GFETs) has been limited largely by parasitic resistances, including contact resistance (R_C) and access resistance (R_A). Measurement of short-channel (500 nm) GFETs with short (200 nm) spin-on-doped source/drain access regions reveals negligible change in transit frequency (f_T) after doping, as compared to ~23% f_T improvement for similarly sized undoped GFETs measured at low temperature, underscoring the impact of R_C on high-frequency performance. DC measurements of undoped/doped short and long-channel GFETs highlight the increasing impact of R_A for larger GFETs. Additionally, parasitic capacitances were minimized by device fabrication using graphene transferred onto low-capacitance quartz substrates. [ABSTRACT FROM AUTHOR]